This invention relates to a line protector for a communications circuit. Such protectors are generally located between outside communications lines and inside equipment, for example, between telephone lines and inside telephone related equipment. Such line protectors generally protect the inside equipment from fault conditions on the outside line, such as overvoltage or overcurrent conditions which may result from lightning, electrical power surges and the like.
Line protectors of the type described are generally classified either as station protectors or as central office protectors. Central office type protectors are generally interposed between central office switching equipment and inside switching-related equipment, and comprise plug-in type modules adapted to be mounted on a common frame having receptacles for receiving a plurality of like protector units to accommodate a plurality of communications lines. Such central office type protectors are shown, for example, in U.S. Pat. Nos. 3,587,021; 3,743,888; 3,794,947; 3,818,271; 3,849,750; 3,886,408 and 3,975,664. Station type protectors generally include a dielectric block having a threaded receptacle for receiving a complementary threaded housing or cap containing a surge arrester. Such a station protector is shown for example, in U.S. Pat. No. 4,013,927. Station protectors are generally interposed between outside telephone lines and inside telephone receivers.
A protector according to this invention, as will be more fully described hereinbelow, is suitable for use as either a central office type protector or as a station type protector. However, the following discussion will be facilitated by specific reference to the protector of this invention embodied as a station type protector.
Station protectors in the prior art have generally been made with a housing, as described above, and related components, specifically designed to cooperate with specific types of arresters. Specifically, a carbon air gap arrester and a two-element gas tube arrester have heretofore been interchangeably accommodated by a given protector design, while a three-element gas tube arrester has heretofore been accommodated by another protector design. Thus, at least two different overall station protector configurations have heretofore been required to accomodate these three types of arresters. Furthermore, existing station protectors include hardware terminations for receiving lines to be protected which are molded in place, and thus capable of receiving only a limited number of lines. Thus, a different protector is required, for example when converting from single pair to multiple pair station protection. Similarly, a plurality of such station protectors may be required in the case where it is desired to protect a plurality of parallel lines, such as required when a plurality of telephone extension receivers are to be protected, thus increasing the cost of such an installation substantially. Such molded in place design therefore requires that different station protectors be fabricated for different applications, which generally leads to increased problems and costs in the fabrication thereof.